1. Field of the Invention
The present invention relates to a semiconductor circuit device such as LSI which is mounted on an electronic equipment such as a computer, and more particularly to a wiring thereof.
2. Related Background Art
The wiring metal for LSI may be commonly a metal containing Al as the main component or pure Al, or a metal containing Al as the main component and a slight amount of Si or Cu. To meet the demand of faster speed and a higher density, the film thickness and the line width of the Al wiring have been reduced. However, the breaking of wire due to the electric current flow, or the disconnection failure due to a so-called electro-migration, or a so-called stress migration due to being subjected to a high temperature, may reduce the reliability of the Al wiring, making it difficult to make a minute structure.
The wiring metal is crystallographically polycrystalline. Conventionally, with such an Al wiring, it has been known that the disconnection failure due to the electro-migration may be caused by the occurrence of voids or hillocks at a grain boundary of each crystal grain, or the occurrence of voids or hillocks within a crystal grain. Also, regarding a polycrystal Al wiring, there is a report that the electro-migration resistance (thereinafter referred to as the EM resistance) of a {111} oriented Al is superior to a {100} oriented polycrystal.
However, the {111} oriented polycrystal and {100} oriented polycrystal only have a lattice plane parallel to a wiring metal surface which is {111} or {100} plane. Thus, voids or hillocks often occurred if the wiring was formed using a polycrystal Al film. Although there is a report that a single crystal Al has been preferably used as the wiring, the EM resistance was often not as excellent as expected.
Thus, the present inventors have found a causal relation between the current flow direction and the void or hillock arising positions, and a qualitative relation between the current direction and the crystal axis. This came about as a result of analyzing a crystal structure of an electrically conductive thin film composed of a crystalline material consisting of a polycrystal or single crystal with a special measuring method.
The above measuring method is a simple evaluation method which allows for a nondestructive measurement of how the plane parallel to a wiring surface and the plane perpendicular thereto are directed with respect to the crystal axis of crystal grain of a polycrystal thin film, using a scan-type .mu.-RHEED microscope. In Japanese Journal of Applied Physics 29 (1989) L2075, is described the scan-type .mu.-RHEED microscope.